$ 3 (e)] VALVE MOVEMENT AND STEAM ACTION. 17 the latter is at its extreme position, together with the volume of the steam-port. The pressure at A is nearly that of the steam in the boiler; but it drops off toward B because the gradual closing of the port chokes the entering current. (f) THE STEAM-CYCLE COMPLETED.-From B to C there is expan- sion of the steam enclosed in the cylinder, as already stated. The 18- 14 15 13 17- 20 21 1211 8 6 16 22 27 24 28 22 29 23 37 38 33 36 39 FIG. 11. The Crosby Indicator. two parts of the exhaust are shown by the drop of pressure from C to D, followed by expulsion at nearly constant pressure along DE. Compression from E to F, raising the pressure in the clearance part way up to that of the fresh steam, completes the cycle. In describing Fig. 9, we considered only the left or head end of the cylinder; there is, of course, a similar action in the other, the crank
